Conventional eyewear is generally catalogued into two groups. The first group includes swimming or diving goggles characterized by waterproof seals when the eyewear is in use. In this group, lenses are firmly secured to the eyewear structure, usually by flexible or semi-flexible sealing devices either integrated with the frame structures or additionally attached thereto, and flexible or semi-flexible seals are also provided to the frame structures to abut the user's face around the eyes in order to prevent water from contacting the user's eyes.
A second group of eyewear includes a variety of eyeglasses, protective work glasses and a particular type of sports glasses or goggles, which are all characterized as having no special sealing requirements in contrast to the swimming or diving goggles, and as permitting air ventilation. The lenses of eyewear are often in direct contact with or in a closely spaced relationship with certain areas of the face of the user such as the cheeks and the super-orbital arches. In such cases when the face perspires and the lenses are relatively cool or when the lenses are worn from a cold atmosphere into a warm moist atmosphere, moisture condenses on the surfaces of the lenses next to the face because circulation of air over the surface of the lens between the lens and the face of the user is limited, particularly when the eyewear frame is curved to fit the user's face. Conventionally, enhanced circulation of air over the surface of the lens between the lens and the face of the user is achieved by providing specially designed air passages through the frame structures or through the lenses of the eyewear.
In another aspect of the eyewear, although the lenses can be replaced, for example when broken, they are generally not designed for interchangeable use. In today's lifestyle however, an eyewear user often needs more than one eyewear to meet various vision needs, whether for functional or styling reasons. For example, a sunglass user may prefer a selected styling for general use, but prefer sunglasses with better ventilation when used during sports activities.
Therefore, improved eyewear is desirable in order to overcome the shortcomings of conventional eyewear and to provide more variety for user selection.